Power semiconductor components, and power electronic circuits constructed therefrom, are very often integrated into so-called power semiconductor modules (or power electronic modules). For example, power electronic converters (for example frequency converters, power inverters, etc.) may be integrated in a power semiconductor module. Power electronic converters constructed with the aid of power transistors (for example MOSFETs or IGBTs) may, for example, be used to drive electric motors. Another application involves inverters which, for example, convert direct current from solar plants into alternating current, so that the latter can be fed into the public power grid. Not only in these applications may current measurement in the load current paths be desirable. When driving electric motors, the motor torque may, for example, be determined from the measured current.
One very simple way of measuring current is to pass the load current to be measured through a measurement resistor (shunt resistor) with a known resistance, and to measure the resulting voltage drop across the measurement resistor. This voltage drop is proportional to the current of interest. In the case of high powers (for example more than 20 kW for electric motors in electrical vehicles), very heavy currents occur (for example up to 100 A or more) and the measurement resistors must be kept with very low resistance (for example in the range of a few milliohms) in order to be able to keep the power loss as small as possible. Since the temperature of the measurement resistor may vary because of the power loss dissipated in the measurement resistor, a low temperature gradient of the resistance is desirable for such measurement resistors. It may be advantageous nevertheless to cool the measurement resistors in order to keep the temperature in a defined range. When the measurement resistors are built into the power semiconductor module, sufficient cooling is normally ensured since during operation the module generally in any case is coupled to a cooling system. Known measurement resistors which are suitable for being built into a power semiconductor module, and for measuring heavy currents, are relatively large and occupy significant space in the module.